Cooling systems such as those used in residential and commercial buildings typically include at least one compressor that circulates refrigerant between an evaporator and a condenser to provide a desired cooling effect. The compressor may be tied either directly or indirectly to a thermostat capable of controlling operation of the compressor and, thus, operation of the cooling system. The thermostat is typically disposed in an area within a residential or commercial building that is centrally located or is otherwise indicative of the temperature within the building.
The compressor associated with the cooling system may output pressurized refrigerant at more than one capacity. Such compressors allow the thermostat to choose between a full-capacity mode and a reduced-capacity mode to more closely match compressor output with the cooling requirements of the building.
An actuation device, such as a solenoid, may be used to modulate compressor capacity between the reduced-capacity mode and full-capacity mode by selectively providing leak paths between a non-orbiting scroll member and an orbiting scroll member of the compressor. The leak paths are achieved by selectively separating the scrolls—radially or axially—to reduce the ability of the scrolls to compress refrigerant.
The solenoid may be selectively supplied with power to toggle the compressor between the reduced-capacity mode and full-capacity mode and typically experiences a rise in temperature due to the supplied power. Furthermore, because the solenoid interacts with at least one of the orbiting scroll member and the non-orbiting scroll member, the solenoid may be partially disposed within a shell of the scroll compressor and additionally experience a rise in temperature due to operation of the compressor. Operation of the solenoid under increased temperature conditions either caused by power supplied to the solenoid and/or lack of refrigerant circulation within the compressor may adversely affect the performance and durability of the solenoid.
Operation of the solenoid under certain operating conditions of the compressor may damage the solenoid and/or compressor. For example, if the compressor experiences a low-side fault, such as a loss of suction pressure, or is simply off, refrigerant is not circulated through the compressor and the solenoid may overheat, if operated. Any other operating condition where the compressor fails to operate (i.e., a locked rotor condition, an electrical fault such as a faulty fan capacitor, an opening winding circuit, etc.) will similarly cause the solenoid to overheat, if operated, and may cause damage to the solenoid and/or compressor.